The invention relates to a display device having a vacuum envelope, said display device comprising an electroluminescent screen and a row of transport ducts for transporting electrons, means for generating electrons and injecting electrons into the transport ducts, means for applying potential differences across the transport ducts to transport electrons through said transport ducts by means of secondary emission, means for extracting electrons from the transport ducts and means for directing electrons towards the electroluminescent screen.
A display device of the type mentioned in the opening paragraph is described in EP-A 0 436 997 corresponding to U.S. Pat. No. 5,347,199. In EP-A 0 436 997 a description is given of a display device in which the means for generating and injecting electrons comprise a line cathode which generates electrons which are injected into the transport ducts by means of electrodes. In general, the aim is to obtain display devices which are constructed so that, in operation, the electron flows in the transport duets do not deviate from a desired value or deviate so little that it is not disturbing or only to a very small degree. Variations in electron flows, both in one transport duct and between transport ducts, cause a deterioration of the picture quality.